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Seven Dangerous Myths About Weight Loss -- Or Are They Little White Lies?

The cover copy of a thousand magazines was attacked this morning in the august pages of the New England Journal of Medicine by Krista Casazza, David B. Allison, both from the University of Alabama, Birmingham, and a long list of co-authors. Much of what you’ve been told about weight loss is wrong and, in the current style of journalists everywhere, they break these misconceptions down into a list of widely-held myths, which they then attack with dry academic savagry.

1. Eating a little less and exercising a little more, over the long term, won’t produce large, long-term weight changes. For a half century, experts have talked about the 3,500-kilocalorie (kilocalories are what we call “calories” in everyday speech). That means for every 3,500 calories you burn or don’t consume, you lose a pound. But this rule was derived from short-term studies. More recent data, the authors say, shows that people lose much less weight when they burn it over a longer period of time.

2. It’s not important to set realistic weight loss goals to avoid frustration. Be ambitious instead. Two studies, the authors say, actually show that interventions designed to improve weight-loss by setting more realistic goals did not lead patients to lose more weight, and several studies show more weight loss with aggressive goals.

3. There’s no reason to think that slow, gradual weight loss is better over the long-term compared to losing lots of weight fast. A pooled analysis of randomized clinical trials that compared rapid weight loss and slow weight loss (or, to be more precise, extreme diets and less grueling ones) found that though the extreme diets resulted in the loss of 66% more weight (16% of body weight versus 10% for the regular diets), there was no difference at the end of a year.

4. There’s no reason to make sure patients are ready for weight-loss treatment. Actually, studies don’t show that measurements of how ready people are to begin dieting, once they seek out a weight loss plan, have any predictive value about how much weight people will eventually lose.

5. Physical education classes don’t play much of a role in preventing childhood obesity. Studies show that phys ed, as it currently exists, doesn’t have a significant impact on obesity.

6. Breast-feeding doesn’t protect against obesity later in life. The authors argue that breastfeeding, despite statements by the World Health Organization to the contrary, doesn’t prevent obesity. Instead, they argue, this is the effect of researchers only publishing breast feeding studies when they have a positive result.

7. Sex doesn’t burn that many calories. Despite the many times you’ve heard that sex burns between 100 and 300 kcals, that’s based on an old, small study. More recent estimate: 14 kilocalories, on average.

Maggie Fox at NBC, who did a wonderful write-up of the New England Journal article, points out that a lot of the authors disclose financial ties to drug or device makers. She quotes NYU’s Marion Nestle saying that the study only makes sense if “the only things that work are drugs, bariatric surgery, and meal replacements, all of which are made by companies with financial ties to the authors.” The worry is that this is just another way to deliver patients to Allergan, which makes the Lap-Band surgical device, or Vivus and Arena Pharmaceuticals, which make newly approved obesity drugs.

There’s a point to that. I’m a great believer in clinical trials, but it’s always important to remember that just because a clinical trial does not show an effect doesn’t mean that effect doesn’t exist — although it always means that effect is smaller than you hoped. Every single one of these myths seems likely to me to have seemed like a little white lie when told by an individual doctor to an individual patient. Saying that just dieting and exercising a little helps likely gets a lot more patients dieting and exercising; likewise, patients are probably less scared by the prospect of gradual weight loss; breastfeeding may prevent infection and raise IQ; telling people sex can be part of their workouts can be encouraging.

But I agree with the authors that, on a larger scale, these myths are harmful: because we can’t set good public policy about obesity if we’ve convinced ourselves that approaches that work don’t. And although I’m not sure how perceiving these myths as true would impact peoples’ weight loss (the myths wouldn’t help, but I’m not sure they hurt) the way we repeat them almost certainly leads to a sense that scientist understand weight loss far better than they do. On the flip side, there is undoubtably a benefit to keeping the conversation about weight loss going in an appealing way — that’s exactly why people in white lab coats tell little white lies. The problem facing us, is, essentially, the Dr. Oz problem: how do we have an appealing conversation about health without repeating balderdash? This is one of the big problems of medicine, and we are not close to solving it.

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I totally agree with you! Then they get discouraged and gain the weight back. The most important issue here is that there is obesity, that people do many stupid things in order to lose weight fast, end up with eating disorders, and besides, 95% of those who lose weight sadly gain it back because of flawed thinking.

The skin eventually tightens up. whether being overweight w/ little saggy skin (yes it will still be saggy) or small with lots of saggy skin. it will take the same amount of time to look good so it really doesnt matter. What truly discourage people is if they dont lose weight.

“There’s a point to that. I’m a great believer in clinical trials, but it’s always important to remember that just because a clinical trial does not show an effect doesn’t mean that effect doesn’t exist — although it always means that effect is smaller than you hoped.”

Actually, as is the case with many JAMA articles, the presence or lack of an observed effect can say more about study design than the hypothesis, especially when you get into areas like weight loss. In the lab, we know exactly what dose was received by our cells or mice, and when. In dealing with patients, you have no idea if they are telling you the truth – about what they’re weight loss goals were, how they feel about their self-image, what they ate for breakfast today, etc.

In one JAMA study the authors asked people who had already had angioplasty what they ate the previous day. They then assumed 1. that patients would be honest and tell their docs if they had been eating things that were ill-advised, like boxes of donuts for lunch, 2. that what the patients claimed they ate the previous day was representative of their daily diet over the previous two years, and 3. that the degree of CAD seen in the subsequent catheterizations was only related to what these patients had supposedly eaten over the last two years, and the fact these patients previously had blockages had no relevance in applying these findings to a healthy population.

The myths here are that any study published in JAMA was done well, that you can somehow weight the results of a meta-analysis without bothering to examine the experimental design of the individual studies in which the data being analyzed was actually generated, and that if you do a meta-analysis of a bunch of lousy clinical studies while ignoring their methodology you can somehow get meaningful quantitative results.

Sorry, NEJM, not JAMA, though they are essentially the same. I mean, it’s not like the NEJM editors didn’t know this article would garner lots of free publicity and wind up in the news, is it? And, now that I’ve looked at the actual article, I see it’s not even a meta-analysis, but a very limited, cherry-picked collection of publications chosen to make the authors’ points.

In reading some of the sections, it becomes evident that the authors are simply repeating conclusions they read in the abstracts without in any way evaluating the methodology or data (or presenting contradictory evidence) .

This article, while having an attractive title for media pundits, is just openly biased data selection and interpretation. It’s not science.

PS If you do a Pubmed search for “weight loss study” you’ll get back 38,383 articles. But, sure, the twenty or so articles mentioned hear were randomly chosen and not hand-picked to make the authors’ points/sell their products…

Losing weight has a lot to do with what you’re eating and more important NOT eating. You should check out this article that contains 5 foods you should completely avoid to lose weight! Helped me a lot and they mention that you don’t even need diet pills to lose the weight! :) http://foodstonevereat.blogspot.com

A lot of these seem to be based on individual variable. Setting small goals isn’t intended to increase weight loss. Based on a performance psychology standpoint, it is aimed at lowering the attrition rate of people who are trying to lose weight. Also, I believe education is important because it helps children understand the importance of playing outdoors instead of playing video games; however, in the end, the fault is all on the heads of the parents. We cannot expect children to make decisions by themselves.

Interesting that they don’t mention metabolism, which many people still think is seriously impacted if you don’t eat every three to four hours. I just did an article about intermittent fasting and found a slew of research and data showing no significant difference from short term (12-72 hour) fasting.

(If you’re interested in reading more on this, the most comprehensive info on fasting/metabolism I found was at www.precisionnutrition.com/intermittent-fasting, though I may also shamelessly plug my own article when it’s published).

Now there is a myth that could make a big difference if it was properly debunked (especially with the health/fitness industries growing as quickly as they are).

#3- If you lose weight too fast, you risk losing your gallbladder and having other health problems. I lost 5 pounds a week because a doctor put me on a much more drastic diet then my age and weight required. I had to have two emergency surgeries and was jaundice for over a week. Looking only at the number on the scale at the end of the year is not enough to support #3.

That’s a great point. The arguments cited in the NEJM article are not examples of saying “don’t lose weight so aggressively that you hurt yourself” but of magazine articles taht said losing weight slowly is more effective than losing weight quickly, i.e., you’ll keep the weight off. I suspect that this is a discussion that would work better with actual numbers.

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There are several ways to lose excess weight safely. The fastest and simplest way to lose some excess weight is to eat less salt and salty food (i.e. less salt, not less food). This reduces the fluid retention that is a factor in all obesity. Unfortunately this is the least recognised way to lose weight.

If you have gained a lot of weight from taking prescription drugs then I suggest you try cutting down on salt/sodium. You will lose weight rapidly, safely and easily. This is because so many drugs have sodium and water retention as side-effects, and so, if you were not told about the need to avoid added salt, weight gain and obesity were all but inevitable.